Variable speed signs (VSS) are used to report variable speed limits in certain areas. VSS allow operators to adjust (e.g., raise or lower) the posted speed limit without changing a physical sign. The signs may be used in conjunction with intelligent transportation systems to adjust speed limits for several reasons including congestion, construction, accidents, or weather conditions. As technology advances, the ease of use of VSS is also increasing. Reported speed limits may be changed on the VSS remotely via email or telephone, at specific times of day, or manually via a control panel. VSS also may be used to alter speed limits based on real time traffic, weather conditions, or construction.
Municipalities (e.g., traffic management centers) that control the VSS may be unwilling to communicate the real time speed limits displayed on the VSS to third parties. In addition, automatic techniques for reading speed values from a VSS remain unreliable. Accordingly, there is a continuing effort to provide improved systems and methods for determining speed values from a VSS.